21851402 has 4 divisors (see below), whose sum is σ = 32777106. Its totient is φ = 10925700.

The previous prime is 21851399. The next prime is 21851407. The reversal of 21851402 is 20415812.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 18395521 + 3455881 = 4289^2 + 1859^2 .

It is not an unprimeable number, because it can be changed into a prime (21851407) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5462849 + ... + 5462852.

Almost surely, 2^21851402 is an apocalyptic number.

21851402 is a deficient number, since it is larger than the sum of its proper divisors (10925704).

21851402 is a wasteful number, since it uses less digits than its factorization.

21851402 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10925703.

The product of its (nonzero) digits is 640, while the sum is 23.

The square root of 21851402 is about 4674.5483204263. The cubic root of 21851402 is about 279.5716323963.

The spelling of 21851402 in words is "twenty-one million, eight hundred fifty-one thousand, four hundred two".